Fan assembly

ABSTRACT

A fan assembly is mainly provided with a center hub and a plurality of fan blades. The center hub has a center rotational axis. The fan blades extend from the center hub. Each of the fan blades has a leading surface and a trailing surface. The trailing surface of at least one of the fan blades includes an intake opening disposed at a first radial distance from the center rotational axis and a jet disposed at a second radial distance from the center rotational axis. The jet is in direct fluid communication with the intake opening such that during operation of the fan assembly airflow is directed from the intake opening to the jet for reducing power required to operate the fan assembly.

BACKGROUND

1. Field of the Invention

The present invention generally relates to fans for use in automotive orother technologies. More specifically, the present invention relates toa fan having at least one fan blade designed to reduce the powerrequired to operate the fan.

2. Background Information

Many different types of fans are presently available. One popular typeof fan is an axial flow fan, which blows air in an axial direction withrespect to the axis of rotation of the fan blades. Axial flow fans areused in a wide variety of cooling applications such as in automotive orother technologies. Typically, a conventional axial flow fan has a hubwith a center rotational axis and a plurality of fan blades that extendgenerally outward in a radial direction with respect to the centerrotational axis of the hub. Each fan blade has two main surfaces (i.e.,a leading surface and a trailing surface). The leading surface primarilycontacts the air during rotation of the fan blades, thus moving the air.The trailing surface is opposite of the leading surface where the air isbeing sucked towards the fan blades. During operation of the fan, theleading surface of each blade has a combination of forces impartedthereon due to contacting the surrounding air. These combinations offorces create a resultant force that is opposite to the direction ofrotation of the fan. Additionally, the rotation of the fan bladescreates a low pressure region behind the distal ends of the trailingsurfaces of the blades, which further increases the resultant forces. Tooperate the fan at a fixed speed, power equal to the resultant forces isrequired.

SUMMARY

It has been discovered that a reduction in the low pressure regionbehind the distal ends of the trailing surfaces of the fan blades candecrease the resultant forces acting on the fan blades. Thus, a fanassembly is proposed that seeks to reduce the power required to operatethe fan by utilizing a flow channel to increase the pressure of the lowpressure region behind the distal ends of the trailing surfaces of thefan blades.

In view of the state of the known technology, one aspect of the presentinvention is to provide a fan assembly that mainly comprises a centerhub and a plurality of fan blades. The center hub has a centerrotational axis. The fan blades extend from the center hub. Each of thefan blades has a leading surface and a trailing surface. The trailingsurface of at least one of the fan blades includes an intake openingdisposed at a first radial distance from the center rotational axis anda jet disposed at a second radial distance from the center rotationalaxis. The jet is in direct fluid communication with the intake openingsuch that during operation of the fan assembly airflow is directed fromthe intake opening to the jet to reduce power required to operate thefan assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a left side elevational a vehicle equipped with a fan assemblyin accordance with an illustrated embodiment;

FIG. 2 is an overall schematic of a vehicle engine with a coolant systemincluding a fan, a radiator and a heater core;

FIG. 3 is a front (leading surface) side elevational view of the fanassembly in accordance with the illustrated embodiment;

FIG. 4 is a rear (trailing surface) side elevational view of the fanassembly in accordance with the illustrated embodiment;

FIG. 5 is an enlarged, rear (trailing surface) side elevational view ofone of the fan blades in accordance with the illustrated embodiment;

FIG. 6 is an top edge view of the fan blade illustrated in FIG. 5 inaccordance with the illustrated embodiment;

FIG. 7 is a transverse cross sectional view of the fan blade illustratedin FIG. 5 as seen along section line 7-7 of FIG. 5 at the intakeopening;

FIG. 8 is a transverse cross sectional view of the fan blade illustratedin FIG. 5 as seen along section line 8-8 of FIG. 5 at a portion of thechannel that provides direct fluid communication between the intakeopening and the jet holes

FIG. 9 is a transverse cross sectional view of the fan blade illustratedin FIG. 5 as seen along section line 9-9 of FIG. 5 at one of the rows ofthe jet holes; and

FIG. 10 is a cross sectional view of the fan blade illustrated in FIG. 5as seen along section line 10-10 of FIG. 5 to show the airflow throughthe fan blade.

DETAILED DESCRIPTION OF EMBODIMENTS

Selected embodiments will now be explained with reference to thedrawings. It will be apparent to those skilled in the art from thisdisclosure that the following descriptions of the embodiments areprovided for illustration only and not for the purpose of limiting theinvention as defined by the appended claims and their equivalents.

Referring initially to FIGS. 1 and 2, a vehicle 10 is illustrated thatis equipped with a pair of fan assemblies 12 in accordance with anillustrated embodiment. As seen in FIG. 2, the fan assemblies 12 arepart of a coolant based climate control system 14 for an engine 16. Inthis illustrated embodiment, one of the fan assembly 12 is driven by theengine 16 via a fluid coupling attached to the water pump pulley, whilethe other one of the fan assemblies 12 is driven by an electric motor.The parts of the coolant based climate control system 14, other than theassembly 12 are conventional components. In addition to the fanassemblies 12 and the engine 16, the coolant based coolant system 14 ismainly provided with, among other things, a compressor 18, a condenser20, an expansion valve or orifice 22, an evaporator 24, a heater core 26and a radiator 28. The compressor 18, the condenser 20, the expansionvalve or orifice 22 and the evaporator 24 constitute a refrigerantcircuit for the air conditioner of the vehicle 10. The engine 16, theheater core 26 and the radiator 28 constitutes a heater circuit for theheater of the vehicle 10. These components 16, 18, 20, 22, 24, 26 and 28are conventional components that are well known in vehicles. Since thesecomponents 16, 18, 20, 22, 24, 26 and 28 are well known, the structuresof the components 16, 18, 20, 22, 24, 26 and 28 will not be discussed orillustrated in detail herein.

The fan assembly 12 that is disposed in front of the condenser 20 is a“pusher fan” configuration, while the fan assembly 12 that is disposedin behind the radiator 28 is a “pulling or suction fan” configuration.In other words, the assembly 12 associated with the condenser 20 pushesair through the condenser 20, while the fan assembly 12 associated withthe radiator 28 sucks air through the radiator 28.

Turning now to FIGS. 3 and 4, the fan assembly 12 is mainly providedwith a center hub 30 and a plurality of fan blades 32. The center hub 30has a center rotational axis A with the fan blades 32 rotating in arotational direction R about the center rotational axis A. The fanblades 32 extend generally outward in a radial direction with respect tothe center rotational axis A of the hub 30. The fan blades 32 extendfrom the center hub 30. Each of the fan blades 32 has a leading surface34 (FIG. 3), a trailing surface 36 (FIG. 4), a hub end 38 and a distalor free end 40.

The leading surface 34 primarily contacts the air during rotation of thefan blades 32, thus moving the air. The trailing surface 36 is oppositeof the leading surface 34 where the air is being sucked towards the fanblades 32. During operation of the fan assembly 12, the leading surface34 of each blade 32 has a combination of forces imparted thereon due tocontacting the surrounding air. These combinations of forces create aresultant force that is opposite to the direction of rotation of the fanassembly 12. Additionally, the rotation of the fan blades 32 creates alow pressure region behind the distal ends 40 of the trailing surfaces36 of the blades 32, which further increases the resultant forces. Tooperate the fan assembly 12 at a fixed speed, power equal to theresultant forces is required.

As seen in FIG. 3, the trailing surface 36 of each of the fan blades 32includes an intake opening 42 disposed at a first radial distance D1from the center rotational axis A and a plurality of jet holes 44disposed at a second radial distance D2 from the center rotational axisA. In the illustrated embodiment, the intake opening 42 is disposed onthe trailing surface 36 of the blade 32 nearer to the hub 30 than thejet holes 44, which are located on the distal half of the trailingsurface 36 of the blade 32. Preferably, the intake opening 42 ispositioned adjacent the center hub 30. Each of the fan blades 32 furtherincludes an airflow channel 46, which is disposed between the leadingsurface 34 and the trailing surface 36 of the corresponding one of thefan blades 32. The airflow channel 46 extends from the first radialdistance D1 to the second radial distance D2 between the intake opening42 and the jet holes 44. Thus, the airflow channel 46 provides directfluid communication between the intake opening 42 and the jet holes 44.Each of the jet holes 44 has a smaller cross sectional area than a crosssectional area of the intake opening 42. Likewise, each of the jet holes44 has a smaller cross sectional area than a cross sectional area of aairflow channel 46 that provides direct fluid communication between theintake opening 42 and the jet holes 44. In the illustrated embodiment,the diameters of the jet holes 44 in each row gets smaller or stays thesame as the rows of the jet holes 44 approaches towards the centerrotational axis A. Also in the illustrated embodiment, the number of thejet holes 44 in each row gets smaller or stays the same as the rows ofthe jet holes 44 approaches towards the center rotational axis A.

The jet holes 44 are in direct fluid communication with the intakeopening 42 such that during operation of the fan assembly 12 airflow isdirected from the intake opening 42 to the jet holes 44 to reduce powerrequired to operate fan assembly 12. In other words, this arrangement ofthe jet holes 44 being in direct fluid communication with the intakeopening 42 reduces the power required to operate the fan assembly 12.The reduction in power to operate the fan assembly 12 is due to theBernoulli Effect, whereby air at a first location corresponding to thejet holes 44 with a higher rotational speed will have lower pressurethan air at a second location corresponding to the intake opening 42where the rotational speed is lower. By providing the airflow channel 46within the blade 32, air flows from the high pressure area of the intakeopening 42 to the lower pressure area of the jet holes 44. The air thenflows out of the jet holes 44 to increase the air pressure in lowpressure region that is behind the distal end 40 of the trailing surface36 of the blade 32 to reduce the power needed to operate the fanassembly 12. This results in a reduction in the net aerodynamic drag onthe fan blades 32 such that the fan blades 32 can deliver air moreefficiently to the trailing blade 32 in its wake, which translates intoless work in the process of generating airflow as compared toconventional designs.

In the illustrated embodiment, the fan blades 32 are all identical toeach other. In other words, the locations and dimensions of the intakeopening 42, the jet holes 44 and the airflow channel 46 are the same ineach of the fan blades 32. However, it will be apparent to those skilledin the art from this disclosure that the fan blades 32 do not need to beall identical to each other. The number of the jet holes 44 can bedifferent between each of the fan blades 32 as needed and/or desired.For example, a single jet (only one of the jet holes 32 can be in one ofthe fan blades 32 as needed and/or desired. Alternatively, only one orsome of the fan blades 32 can be provided with an airflow passage (i.e.,the intake opening 42, the jet holes 44 and the airflow channel 46).Also, while the jet holes 44 are circular holes in the illustratedembodiment, it will be apparent to those skilled in the art from thisdisclosure that the jet holes 44 can have other shapes as needed and/ordesired. In the illustrated embodiment, the jet holes 44 are located ona distal half of the blade 32 with the jet holes 44 being spacedinwardly from the radially extending edges of the trailing surface 36.

In the illustrated embodiment, the fan blades 32 are mainly constructedof two pieces that are rigidly fixed together. For example, in theillustrated embodiment, each of the fan blades 32 includes a first bladepart 50 entirely defining the leading surface 34 and a second blade part52 entirely defining the trailing surface 36, with the first and secondparts 50 and 52 being physically separate piece that are joined togetherin suitable manner. Also in the illustrated embodiment, each of the fanblades 32 is formed of a hard rigid plastic material such as thosecommonly used in automotive fan blades. When the fan blades 32 areformed with the first and second blade parts 50 and 52, the intakeopening 42 and the jet holes 44 are preferably formed on the first bladepart 50 of the fan blade 32, while the airflow channel 46 is preferablyformed between an interface of the first and second blade parts 50 and52. In this way, the airflow channel 46 can be easily formed.

Of course, it will be apparent to those skilled in the art from thisdisclosure that the fan blades 32 can be formed in other ways to producethe airflow passages (i.e., the intake openings 42, the jet holes 44 andthe airflow channels 46). For example, although a two-piece constructionis illustrated, it will be apparent to those skilled in the art fromthis disclosure that each of the fan blades 32 can be a unitary member(e.g., formed using conventional blow molding techniques).

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. For example, the size, shape, location ororientation of the various components can be changed as needed and/ordesired. While the airflow channel 46 is disposed entirely within thefan blade 32, it will be apparent to those skilled in the art from thisdisclosure that the airflow channel 46 could even be formed on thetrailing surface 36. Every feature which is unique from the prior art,alone or in combination with other features, also should be considered aseparate description of further inventions by the applicant, includingthe structural and/or functional concepts embodied by such feature(s).Thus, the foregoing descriptions of the embodiments according to thepresent invention are provided for illustration only, and not for thepurpose of limiting the invention as defined by the appended claims andtheir equivalents.

1. A fan assembly comprising: a center hub having a center rotationalaxis; and a plurality of fan blades extending from the center hub, eachof the fan blades having a leading surface and a trailing surface, thetrailing surface of at least one of the fan blades including an intakeopening disposed at a first radial distance from the center rotationalaxis and a jet disposed at a second radial distance from the centerrotational axis, with the jet being in direct fluid communication withthe intake opening such that during operation of the fan assemblyairflow is directed from the intake opening to the jet to reduce powerrequired to operate the fan assembly.
 2. The fan assembly as set forthin claim 1, wherein the at least one of the fan blades further includesa channel that provides direct fluid communication between the intakeopening and the jet.
 3. The fan assembly as set forth in claim 2,wherein the channel is disposed between the leading surface and thetrailing surface of the at least one of the fan blades.
 4. The fanassembly as set forth in claim 2, wherein the channel extends from thefirst distance to the second distance.
 5. The fan assembly as set forthin claim 1, wherein the jet includes a plurality of jet holes.
 6. Thefan assembly as set forth in claim 5, wherein the jet holes are circularholes.
 7. The fan assembly as set forth in claim 5, wherein the jetholes are located on a distal half of the blade.
 8. The fan assembly asset forth in claim 5, wherein the jet holes are spaced in from aradially extending edge of the trailing surface.
 9. The fan assembly asset forth in claim 5, wherein each of the jet holes has a smaller crosssectional area than a cross sectional area of the intake opening. 10.The fan assembly as set forth in claim 5, wherein each of the jet holeshas a smaller cross sectional area than a cross sectional area of achannel that provides direct fluid communication between the intakeopening and the jet holes.
 11. The fan assembly as set forth in claim 1,wherein the intake opening is positioned adjacent the center hub. 12.The fan assembly as set forth in claim 11, wherein the intake openinghas a larger cross sectional area than a cross sectional area of thejet.
 13. The fan assembly as set forth in claim 1, further compriseseach of the fan blades includes a corresponding intake opening disposedat a first radial distance from the center rotational axis and acorresponding jet extending from the center hub disposed at a secondradial distance from the center rotational axis.
 14. The fan assembly asset forth in claim 1, wherein the at least one of the fan bladesincludes a first blade part defining the leading surface and a secondblade part defining at least part of the trailing surface, with thefirst and second blade parts being physically separate pieces that arejoined together.
 15. The fan assembly as set forth in claim 14, whereinthe at least one of the fan blades further includes a channel thatprovides direct fluid communication between the intake opening and thejet, with the channel being formed between an interface of the first andsecond blade parts.
 16. The fan assembly as set forth in claim 15,wherein the jet is formed on the first blade part of the at least one ofthe fan blades.
 17. The fan assembly as set forth in claim 15, whereinthe intake opening is formed on the first blade part of the at least oneof the fan blades.